Pumped storage hydro-electric power is a method of producing electricity to supply high peak power demands by moving water between water reservoirs at different elevations. At times of low electrical demand, excess generation capacity is used to pump water back into the higher reservoir. When there is higher demand, water is released back into the lower reservoir through a turbine. Pumped-storage schemes currently provide the most commercially important means of large-scale grid energy storage. Such systems greatly improve the daily capacity factor of power generating systems though out the world.